I want to set up a mtn bike for touring. It will have 44-32-22 rings and 9 speed SRAM Rocket shifters. I want to use a 12-25 or 12-23 cassette. Will an 8 speed double dura-ace derrailleur work on this set up or should I look at buying a 9 speed triple or double? I do not need to run more than a 25 in the back, and with a 22 front ring a 23 would probably do.